* Cecil Taylor, one of the spunkiest innovators of post-Parker jazz, hunches over a grand piano onstage at UCLA's Royce Hall, his bantam-sized hands pumping constantly, snatching chords where they shouldn't exist and spinning a dense web of jarring atonality. Taylor's music tells of human stuff — torment and revelation — but it isn't a music for the masses. To fathom it, you need to suspend the usual ideas about musical order and beauty. Intriguingly, a mostly young, white audience has packed the hall, apparently willing to do just that.

* Herbie Hancock brings an arsenal of synthesizers to the swank stage of the Dorothy Chandler Pavilion in Los Angeles. Like most of his music since the 1973 Head Hunters, including his recent disco effort, Feets Don't Fail Me Now, the show is steeped in bawdy funk. When he isn't maneuvering back and forth behind his electronic keyboard bank, Hancock spends a lot of time "singing" through a Vocoder—a contraption worn like an operator's headset that synthesizes speech into melody. Unlike Taylor's, this is comforting, carnal music, and the excitable Pavilion crowd — again, mostly young and white — looks willing to be stroked all night.

Jazz has been flaunting its diversity since the early days of this century, but probably never as radically as right now. Yet what's striking is that artists as different as Taylor and Hancock have developed dedicated followings. Jazz today, though nowhere near rock's platinum plateau, is clearly reaching its broadest audience in over a generation. Much more of that audience may prefer Herbie Hancock, Chuck Mangione and George Benson to Cecil Taylor or fellow avant-gardists Carla Bley and Anthony Braxton, but a solid and growing number are listening to such challenging artists as Keith Jarrett, McCoy Tyner and Weather Report.

What's happened is that the fusion and crossover successes of recent years have helped buoy the entire jazz scene. The total number of jazz clubs in New York, Los Angeles, Boston, Chicago and San Francisco has doubled in the last five years, as have the jazz rosters of most major labels. And moderately successful independents, such as Inner City and Muse, release jazz almost exclusively. But not only the contemporary camps have flourished; more than a third of all jazz releases are reissues of classics. (Charlie Parker's Bird/The Savoy Recordings (Master Takes), released by Arista — one of the best jazz collections ever — has reportedly outsold all other reissues.)

Curiously, some observers have referred to all this as the resurgence of a long-dormant art form. JAZZ COMES BACK! announced a Newsweek cover two years ago, as if jazz had just returned from a wayward cruise. In truth, of course, jazz has been tirelessly dynamic for over three-quarters of a century, but that's often been obscured by the overriding success of popular music. In the late Forties—the peak of be-bop fever—Tin Pan Alley and rhythm & blues easily outsold Charlie Parker's best work. In the latter part of the Fifties, while Elvis Presley, Chuck Berry and others were adapting the blues and making black music available to a mass white audience more than anyone had since Benny Goodman, jazz meisters Miles Davis, Charles Mingus, Cecil Taylor and Ornette Coleman were remodeling blues theory altogether.

During the Sixties, John Coltrane, Albert Ayler, Eric Dolphy and Sonny Rollins redefined the music's spiritual and structural purposes; in the early Seventies, Miles Davis, Tony Williams and John McLaughlin helped conceive a music called jazz rock, then fusion. Collectively, Davis and Coleman could never have approached the drawing power that the Beatles and Rolling Stones achieved separately, yet they affected the musical fabric of the last twenty years just as profoundly. We have different ideas now about musical community because of the Beatles; we have different perceptions about melody because of Ornette Coleman.

But now that jazz has become more popular, it seems unable to replenish its diminished supply of leaders. So far in this decade, Louis Armstrong, Duke Ellington and Charles Mingus have died, and Miles Davis, stricken with recurrent hip and leg problems, hasn't performed publicly or released a new record in years.

No younger artist (or movement) in the Seventies has yet been able to catalyze jazz the way Parker, Coltrane and Davis did. The music, of course, still has major stylists, but most of our best artists and groups, including Keith Jarrett and Weather Report, epitomize worthy styles without attempting to transform the idiom. And while Ornette Coleman and Cecil Taylor remain giant innovators and influences, both make music so personal and complex that they seem like movements unto themselves.

Although no one person or group appears to be altering jazz, it's changing just the same, maybe right down to its essence. The definition of jazz usually includes melodic improvisation; a lilting yet tense rhythmic quality known as swing (as in: "It don't mean a thing if it ain't got that..."); and most importantly, an intensely personal phrasing style, generally blues-derived.

But two of the main movements in contemporary jazz — fusion and a Euro-American classical amalgam — may be gradually changing our notions of the form. Fusion is today's real jazz mainstream: it reaches a considerable audience that accepts its pulsations as unadulterated jazz. Many purists have called fusion a demeaning commercial ploy; certainly, as it has become more obsessed with orderly form, funk-dominated rhythm patterns and simple blues scales, the music has become more of a salable exercise and less of a quest. But the same can be said for any developing art form.

What's more subversive about fusion is the way it treats the relationship between melody and rhythm. Particularly in funky fusion, the rhythmic base is often either inflexibly narrow or gaudily complex; either way, it allows for little real interaction with the improvised melody line. It's tough to extemporize creatively over stodgy chock-wocka-wick-wick rhythmic riffs, as Hancock, Grover Washington and George Duke manage to prove so consistently. So while funky fusion may "swing" (or at least grind and hop a lot), it also enforces a circumscribed improvisational style, which means a de-emphasis of individual "voice."

At the other end of the spectrum is a still-forming Euro-American chamber-music school, represented by such groups as Oregon and most of the acts on Manfred Eicher's German-based ECM label (including Pat Metheny, Jan Garbarek, Eberhard Weber, Terje Rypdal and Keith Jarrett). In a sense, much of it is a fulfillment of the modal terrain first staked out by Miles Davis and Bill Evans on Kind of Blue, though Eicher often prefers Western "classical" harmonies and scales over blues ones. Sometimes that makes for resplendently cerebral jazz, in which soloists improvise over fluidly spacial, harmonic planes — the inverse of fusion. Just as often, though, given the stately sensibility, it lacks rhythmic edge and emotional character. Still, Eicher clearly has helped promote European musicianship to a previously unequaled stature in jazz.

But if the fusion and chamber schools appear pivotal in modern jazz, they've hardly scared off their competition. In the last year alone, McCoy Tyner, Sonny Rollins and Ron Carter waged a highly successful American tour as a unique unit; Irakere, a Havana-based Afro-Cuban group, recorded a rousing debut for CBS (becoming the first Cuban group signed in America); the Akiyoshi/Tabackin Big Band continued to tap and embellish Duke Ellington's legacy; Ornette Coleman and Cecil Taylor released their strongest albums in years; and Johnny Griffin, Pete Christlieb, Warne Marsh and Woody Shaw made superb records, reaffirming bop's continual vitality. And the Chicago-cum-New York avant-garde is more exciting than ever, encompassing a wide range of innovators, from the Air trio to the World Saxophone Quartet (Oliver Lake, David Murray, Hamiet Bluiett and Julius Hemphill) to the seminal Art Ensemble of Chicago.

So with all these diverse factions, is jazz crossbreeding, splitting, interfusing or what? It's impossible to tell how deeply it will be changed by its newest and most popular strains (though surely the new audience they've brought in is welcome). Jazz will likely always cling to its blues sonority, but it may transform it as it delves deeper into European, Asian, Latin and even African musical values. Also, the jazz population is changing; in addition to the great increase in listeners, more white musicians are recording jazz than at any time since the swing era. It may well be that the music is becoming less a chronicle of the black American's experience than the meeting place of schooled musical sensibilities, both black and white. And if so, that means great change indeed.